Featherstone Nutrition

Runners often fall somewhere between those who are serious about pre-run fueling and those who don’t fuel at all. The former is great when it’s done right, while the latter can leave runners feeling depleted. Some common reasons runners skip pre-run fueling are:

All of the factors discussed above contribute to many athletes shortchanging their potential progress and gains by not fueling. As we explored in a recent post, you need an ample supply of carbs to utilize as fast-burning fuel, first via glucose in your bloodstream and then from glycogen stored in your muscles and liver. The authors of a study published in the Journal of Sports Sciences wrote that “Carbohydrate availability is increased by consuming carbohydrate in the hours or days prior to the session, intake during exercise, and refueling during recovery between sessions.” 

If you don’t check all three of these boxes, then you’re going to find it difficult to achieve your target pace and stick with it, might start to fatigue sooner, and will feel like you’re working harder than you should be. A position statement from the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine stated that short-term low energy availability leads to decreased muscle strength, reduced endurance capacity, and a blunted response to training. On the mental side, inadequate fueling can also cause lack of focus, mood irregularities, and a loss of coordination that could increase your risk of injury. You probably wouldn’t plan to head out on a road trip if your gas tank was low or even empty, so why would you risk it with your own body? 

The thinking on short runs has typically been that your body has sufficient glucose and glycogen to power you through. But this is based on the premise that you’ve been eating optimally throughout the day and are coming into your training fresh and adequately fueled. The trouble is that you might not be, so if you’re starting from a calorie, carb, or energy deficit, things aren’t likely to go well. When you don’t have enough quick-acting glucose to power your shorter runs (or any activity, for that matter), you’ll need to tap into stored glycogen first and fat second, neither of which are as efficient. Think about the difference between putting small pieces of kindling on a fire versus loading a big log on top – one burns quickly while the other takes time to burst into flames and then break down. 

Another potential issue with going into a shorter run in a fasted state is that it increases your stress response. As a result, your body pumps out cortisol and other stress hormones, putting you in a high-alert, fight-or-flight state. That’s not ideal during what’s supposed to be an easy run, and it will result in you feeling like you’re working harder than usual. Afterward, you might be drained because the overall load of the session is higher due to the increased stress on your body. 

In contrast, if you eat something before a short run, you’ll have sufficient fuel to provide ready energy, hit your performance target with lower perceived exertion, and keep your stress response under control. Another benefit is that you won’t have dug yourself deeper into a deficit, so it will be easier to fully recover. 

So what should you eat before a short run (70 minutes or less)? The simplest answer is a small amount of simple carbs. For fruit, this could be quarter of a cup of raisins or dates or a banana. Good grain-based options include half a bagel, a piece of toast, an English muffin, or a flour tortilla. Seeking a convenient snack? Then consider a PR Tart, serving of pretzels, or two graham crackers. If you’re looking at nutrition labels, 25 to 30 grams of carbs is the sweet spot, but don’t overthink this. Try eating something from the graphic below in the hour before you start your run, along with 8-16 ounces of fluid so you’re hydrated.  

If you’re pushed for time, don’t use this as an excuse to skip fueling. Remember that fast-acting carbs will start to digest in as few as 15 minutes. I get a lot of questions about including fat and protein with pre-training snacks. There’s nothing wrong with this, but as they digest more slowly than simple carbs alone (same goes with fiber), add a bit more time if you’re going to spread butter on your toast, cream cheese on your bagel, or nut butter on your banana. Incorporating protein is a great strategy if you’re snacking one to two hours before a run. If there are three or more hours until you train, you should make your snack a full meal.  

Longer runs (70 minutes or more) present a different fueling challenge to shorter ones because you’re more likely to burn through the glucose in your bloodstream and at least some of your glycogen stores. So there’s an even greater need to fuel up before you head out. A simple rule of thumb is to double the carb portion that you’re eating before short runs (this can also apply to higher intensity shorter sessions, as these place a greater demand on your body and require it to consume more fuel at a quicker rate.) If you’d snack on two graham crackers for a 45-minute steady state session, try eating four prior to a 90-minute one. You can also start combining carb sources, such as a banana with half a cup of oats, two dates and two PR Tarts, or a fig bar and two pieces of toast (check out more suggestions here). 

These quantities should put you into the lower end of the 50-to-90-gram range I typically recommend to clients for longer sessions. You can go a little further by using the equation in the graphic above to determine your carb range, and then consider working with a sports dietitian if you want to really dial in your personalized fueling needs. As you’ll be increasing the amount you’re eating, digestion might take longer so try to eat 30 to 90 minutes before your longer run. 

While you shouldn’t need to refuel during shorter runs, you don’t want to completely burn through your carb stores during longer ones and have to rely solely on fat because it’s a slow energy source and not the preferred fuel source. With this in mind, start intra-run fueling within the first 30 to 45 minutes of longer sessions. The range for carb replenishment is anywhere from 40 to 80 grams an hour depending on body size, intensity, training status, and so on, so you’ll need to experiment a little. A good place to start is 1 serving (25-30g carb) every 30 minutes.

Fuel uptake and hydration are interrelated, so I recommend drinking the same 8-16 ounces of fluid as you would before a short run and carrying additional fluids with you for any session lasting an hour or more. If you’re using a hydrogel, you might need less fluid, but if not, try combining your regular gel (or tab, chew, etc.) with water. When it’s hot and/or humid, consider a sports drink that contains electrolytes so you can replace some of the sodium you are losing through sweat. 

A lot of the runners I work with focus on fueling their distance sessions, but speed training also requires smart fueling, whether that’s hill sprints or track intervals. The authors of the ACSM position paper mentioned earlier states that carbohydrate availability enhances long workouts with high intensity intervals while depleted levels of carbs are associated with reduced work rates, impaired skill and concentration, and increased perception of effort. 

To avoid such side effects and maximize the benefits of your longer speed workouts (70 to 90 minutes), make sure you’re fueling appropriately. This looks a little different to regularly paced runs of a similar duration. It takes more time for fuel and fluid to empty out of the stomach during high-intensity sessions, with one researcher finding that gastric emptying was around 50 percent slower when VO2 max was at 90 percent. This means you’re at greater risk of nausea, cramping, and other kinds of stomach discomfort if you’re sucking down a mid-workout gel. So eat a carb-rich snack beforehand, only use gels during your warmup so they empty from your stomach before the intensity gets too high, and sip a sports drink in between intervals/reps. 

Of the three macronutrients, carbs provide the most readily available fast fuel source, as your body breaks them down into (most abundantly) glucose,  that’s quickly sent into your bloodstream and shuttled to your muscles, brain, organs, and so on. Any extra glucose that isn’t utilized right away is stored as glycogen in your muscles and liver, so it can be put to use later. 

For as much hype as there is around becoming “fat-adapted” and developing greater “metabolic flexibility,” carbs are still the fuel source that’s preferred by your entire body, especially for endurance athletes.  One of the reasons is that while stored fat offers a much larger potential energy reserve than carbs, it takes much longer to tap into this energy when you need fuel immediately during training or racing. While fat can be a valuable energy source for low-to-moderate intensity activities that have a lower energy demand, research has shown that when our bodies are working at the higher end of our VO2 Max, carbohydrates are the fuel source we need to have readily available.

The more miles you put in, and the faster you cover them, the more carbs you need. It’s the optimal fuel for high-intensity performance, providing sufficient energy to power muscle contraction and help you achieve and sustain your target pace. This first comes from glucose in your bloodstream that is available as soon as 15 minutes after you eat simple carbs, and then, from stored glycogen. Low carb intake = low glycogen stores = poor performance. 

Just because more miles and greater intensity should equal more carbs consumed, it doesn’t mean no miles = no carbs. There’s a common misconception among athletes that on days when their program only calls for an easy run or a real rest, they should dramatically cut down on their carb intake or eliminate it altogether. This neglects the fact that even at rest, your body typically gets about 20 percent of its fuel from glycogen, while your brain requires at least 130 grams of carbs per day to function optimally according to the National Academies’ Institute of Medicine, no matter what your training load is. Plus, you need to replenish the glycogen stores that you depleted on a heavy or moderate training day. In other words, stop cutting out carbs when you have a low mileage, low intensity, or off day planned.

Carbohydrates also help our bodies to absorb water and certain electrolytes during training and racing so that you don’t become dehydrated. Research shows that when we consume water + sodium + glucose together, absorption and hydration increases. A study found that a drink containing carbs and electrolytes helped participants finish a 21-kilometer time trial faster and with better visual motor capacity than those who used a placebo.

After training, most of the refueling advice has focused on getting enough protein into your body as quickly as possible to aid muscle repair. This is true, but, if you don’t have enough carbs in your system, this will be less effective, and muscle breakdown can still occur because your body will start using amino acids for energy instead of restoring and building muscle. Combining carbs with protein right after training in a meal, smoothie or shake will not only spare amino acids for repair, but also help you bounce back strong by replenishing the glycogen stores that you depleted during your workout.

We just explored some ways that carbs power performance and recovery. But how do you know when you’re not consuming enough? During your training, you might struggle to hit paces or find that you’re running out of steam earlier than usual. A paper published in Applied Physiology, Nutrition, and Metabolism found that during an intense cycling session, time-to-exhaustion was reduced for participants who were low on carbs and concluded that a low-carb diet “reduces both performance and total aerobic energy provision during supramaximal exercise.” Cutting back on carbs can also hamper your decision-making during and after exercise. 

Some of the side effects of not eating enough carbs – particularly when paired with an overall calorie deficit – can mimic the perils of overtraining, such as increased perceived exertion, excessive and persistent muscle soreness, and hormonal/menstrual cycle disruption. You could also feel like you’re low on energy, fatigued, and more emotionally volatile than usual. If you have trouble falling or staying asleep or wake up feeling like you need another couple of hours in bed, low-carb intake could be partly responsible, with researchers suggesting that this reduces the amount of time spent in REM sleep. 

Fortunately, if you find that you are underfueling, fixing it is easy: eat more carbs! You can do this by choosing foods that contain 70 to 95 percent carbs, including pasta, bread, rice, bananas, and bagels, instead of high fat foods such as french fries, donuts or chips. (Eating these occasionally is totally fine! But, doing it all the time would increase your caloric intake, as well as possibly increasing GI distress due to the higher fat content.) You can use high carb foods as standalone snacks on either side of your workouts, and also incorporate them into breakfast, lunch, and dinner. Then during your training, consider using goos, gels, tabs, sports drinks, and other sources of simple carbs to keep you going. 

 1. “Report Offers New Eating and Physical Activity Targets To Reduce Chronic Disease Risk,” National Academies of Sciences, Engineering, and Medicine, September 5, 2002, available online at https://www.nationalacademies.org/news/2002/09/report-offers-new-eating-and-physical-activity-targets-to-reduce-chronic-disease-risk.2. EM Wright and DD Loo, “Coupling Between Na+, Sugar, and Water Transport Across the Intestine,” Annals of the New York Academies of Sciences, 2000, available online at https://pubmed.ncbi.nlm.nih.gov/11193601.3. Z Gui et al, “Effect of Protein and Carbohydrate Solutions on Running Performance and Cognitive Function in Female Recreational Runners,” PLOS ONE, October 12, 2017, available online at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185982#. 4. Adriano E Lima-Silva et al, “Effects of a Low- or a High-Carbohydrate Diet on Performance, Energy System Contribution, and Metabolic Responses During Supramaximal Exercise,” Applied Physiology, Nutrition, and Metabolism, September 2013, available online at https://pubmed.ncbi.nlm.nih.gov/23905657.5. Ahmad Afaghi et al, “Acute Effects of the Very Low Carbohydrate Diet on Sleep Indices,” Nutritional Neuroscience, August 2008, available online at https://pubmed.ncbi.nlm.nih.gov/23419282.